1. Field of the Invention
The present invention relates to a headrest of inclinable type for use with an automotive seat, which is adjustingly inclinable in the forward and backward directions of the seat to adjust an angle of inclination of the headrest for supporting a head of an occupant on the seat. In particular, the invention is directed to a headrest of this kind provided with a ratchet-type inclination adjustment mechanism wherein a lock gear is normally biased by a spring element into meshed engagement with a ratchet gear to maintain a certain inclination angle of the headrest, but, disengagement and engagement of the lock gear from and with the ratchet gear permits adjustable inclination of the headrest at a desired angle for supporting the seat occupant's head.
2. Description of Prior Art
Among various sorts of headrests, there is known an inclinable headrest having a ratchet-type inclination adjustment mechanism provided therein for adjustment of inclination of the headrest. For example, FIG. 1 shows a conventional ratchet-type inclination adjustment mechanism (RM′) to be provided in a headrest, which basically comprises: a base bracket 10′; a ratchet gear 3; a lock gear 2; and a tension spring 1′. It is to be noted that such conventional ratchet-type inclination adjustment mechanism RM′ is well known in the art.
The base bracket 10′ is of a substantially U-shaped cross-section having: a vertically extending base wall 10′B; and a pair of first and second side walls 10′A and 10′C projecting continuously from two lateral ends of that base wall 10′B, respectively, as seen in FIG. 1.
Reference is now made to FIG. 2. Although this FIG. 2 shows a structure of the present invention which will be elaborated later, it is to be understood that most of the constituent elements forming a headrest HR as well as a ratchet-type inclination adjustment mechanism RM, which are shown in FIG. 2, are known in the art, excepting a base bracket 10, a tension spring mounting area (at 10AR and 11) and a tension spring 1, which are associated with the present invention. Hence, hereinafter, the conventional ratchet-type inclination adjustment mechanism (RM′) will be described, using some of the known constituent elements shown in FIG. 2, for the sake of clarity.
Designation 5 in FIG. 2 denotes a known headrest stay by which the headrest HR is mounted on the top of a seat back SB, the headrest stay 5 having a horizontal upper base portion 50. As understandable from FIGS. 1 and 2, rotatably connected to such horizontal upper base portion 50 of headrest stay 5 are the two lower end portions respectively of the aforesaid two first and second side walls 10′A and 10′C of the base bracket 10′.
As shown in FIG. 1, a lock gear 2 and a ratchet gear 3 are provided inside of the three walls 10′A, 10′B and 10′C of the base bracket 10′. The ratchet gear 3 is fixedly attached to the aforesaid headrest stay's horizontal upper base portion 50, whereas the lock gear 2 is rotatably journalled between the first and second side walls 10′A and 10′B of base bracket 10. The toothed region 21′ of the lock gear 2 is in meshed engagement with the gear region 30 of the ratchet gear 3. A biasing coil spring 4 is wound about the horizontal upper base portion 50 of headrest stay 5, such that one end 41 thereof is connected with the ratchet gear 3, while the other end 42 thereof is engaged in a hole 10′Ch of the base bracket 10′.
While not shown in FIG. 1, the base wall 10′B of base bracket 10′ is fixed to a known suitable conventional frame element securely provided within the headrest HR, on the understanding that this conventional ratchet-type inclination adjustment mechanism RM′ is applied only to the body of the headrest HR.
As constructed above, the base bracket 10′ is free to rotate about the headrest stay's horizontal upper base portion 50, but biasingly caused by the tension coil spring 4 to rotate in a direction rearwardly of the body of the headrest HR. Therefore, the headrest body itself is biased by that biasing coil spring 4 in a rearward direction at R relative to the headrest stay 5. But, the meshed engagement of the lock gear 2 with the ratchet gear 3 locks the base bracket 10′ or the headrest body (HR) against rotation, so that the headrest body is normally locked and retained at a certain angle of inclination relative to the headrest stay 5.
With vertical rotation of the lock gear 2, the toothed region 20 of the lock gear 2 can be meshed with and disengaged from the toothed region 30 of the ratchet gear 3, to thereby allow locking and unlocking of the base bracket 10′ or the headrest body (HR) at a desired angle of inclination.
According to such conventional ratchet-type inclination adjustment mechanism RM′, a tension spring 1′ is shown in FIG. 1 to be provided between the lock gear 2 and the base bracket's first side wall 10′A, so that the lock gear 2 is normally biased by the tension spring 1′ into meshed engagement with the stationary lock gear 3. Specifically, the tension spring 1′ is at one end portion VA thereof engaged in a hole 10′Ah formed in the base bracket's first side wall 10′A and is also at the other end portion 1′B thereof engaged in a hole 21′ formed in the lock gear 2, such that a main body of the tension spring 1′ is interposed between an inner surface 10′A-1 of the base bracket's side wall 10′A and one lateral surface 2W of the lock gear 2.
In this regard, the process of assembling the inclination adjustment mechanism RM′ involves a manual step for a worker to use his or her hands to insert the tension spring 1′ in a space between the base bracket's inner surface 10′A-1 and the lock gear's lateral surface 2W, and then engage the two end portions 1A and 1B thereof in the two holes 10′Ah and 21′, respectively.
However, such space between the two surfaces 10′A and 2W mentioned above is quite narrow, which makes it troublesome and time-consuming for the worker to install and secure the tension spring 1′ between the lock gear 2 and base bracket's first side wall 10′A as described above. To solve such problem, it may be possible to widen the space between the side wall 10′A and lock gear 2, which will however require increasing the size of the base bracket 10′ and thus makes it impossible to design the base bracket in a small size. Even if the base bracket 10′ can be formed in a smaller size, it is still quite troublesome and time-consuming for the worker to manually bring the tension spring 1′ into a narrow space between the base bracket's first side wall 10′A and the lock gear 2, and manage to engage the two ends 1′A and 1′B of that tension spring 1′ in the respective two holes 10′Ah and 21′ as stated above.
In any case, in this prior art shown in FIG. 1, the location for installation of the tension spring 1′ is at the inside of the base bracket 10′ and at a hardly accessible narrow point between the base bracket's inner surface 10′A-1 and the lock gear 2. Moreover, the end 1′B of the tension spring 1′ has to be bent as shown, after having been inserted in the hole 21′ of the lock gear 2, for preventing the removal thereof from that hole 21′. As a consequence thereof, it is extremely difficult for the worker to quickly connect the tension spring 1′ between the base bracket 10′ and the lock gear 2.